#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int arr[9] = { 1,2,3,4,5,1,2,3,4 };
	int a = 0;
	for (int i = 0; i < 9; i++)
	{
		a ^= arr[i];

	}
	printf("%d", a);
	return 0;
}